avc-r injector duty cycles?
 

I have an apexi avc-r in my car and when i monitor the injector duty cycle it is at like 95-96% at 750 rmp idle and goes down with more throttle ( to like 20% at the lowest i think but its hard to tell cause it does not save the low % only the highest % at idle) and i dont like going full throttle without looking at the road.... But anyway I have a feeling there is a reversed wire cause this seems backwards to me, I am just figuring out how to realy work this thing and I did not install it. Is it just crossed wires and where do they connect, the ecu? also at 750 rpm idle is -410 mm/hg vacum a normal reading? I thinks thats about 17 psi vac.

my injector duties never change from 33-34%...i don't know what the hell is the deal

ok my bad here I was unaware that the vaccume part of my manual boost controler is in in/hg ( thought it was psi!) and was usin that for the conversion.... the readings i just got at idle are -450 mm/hg on the apexi and -17 in/hg on the manual gauge, wich is about -8 psi? realy want to know if my injector duty cycle monitor lines are crossed tho :confused:

arent the inj. duty cycles sposed to increase with the demand for more fuel???

First off, vacuum and boost are measured in different units. Using SAE standards, vacuum is in inches of mercury and boost is in pounds per square inch. Metric boost is either bar or kilograms per centimeter squared, and vacuum is millimeters of mercury.

Injector duty is WAY off - it should only be a few percent at idle, then increase with RPM's and load. But, reading the injector pulsewidth will be weird, since primary and secondary injectors can have different pulsewidth.

Dale

My experience with the AVC-R is that there are two ways to hook up one of the wires, and only one of them works for reporting injector duty cycle. I don't have the manual handy, but I think the way that works for both injector duty and RPM is hooking it to one of the primary injector circuits. I think the other way only gives RPM but not injector duty. However, that is from memory and I could be way off. You clearly have some problem with how you connected it, as injector duty should be low at idle, climb until the switch to primary+secondary injector operation, and then climb again with boost and RPM to redline. Look at the instructions and perhaps the factory shop manual (to see what the ECU pins connect to), consider which method to connect the wires makes the most sense (as I mentioned, the manual lists two different possibilities for one of the wires -- if you aren't hooking to an ), and then hook it up and see if it works. Revise the connections if it doesn't work as expected.

Another thing I have noticed with the injector duty cycle readings on the AVC-R is that I sometimes get a false reading of 100% (or close to that). I think this happens when the ECU cuts fuel on deceleration or something like that. I don't know any solutions for this, but it only really matters when you are looking at peak values, so it isn't that much of a problem. It reads correctly otherwise.

-Max

congrats on running the AVC R... it is a fabulous boost controller and general resource. it appears that your inj duty cycle wire isn't hooked up to the right port in your ecu. it should be reading somewhere around 5% at idle.

howard coleman

Let me try to explain a lil better...

The inj. duty cycles I am getting on the avc-r apear to be accurate but reversed. At idle it is registering 96% and goes down with throttle to 80, 70, 60..ect depending on load and rpm like u said, BUT this is BACKWARDS! It is showing me the AVAILABLE duty cycle not the current duty cycle, if u get what i mean. And this is useless to me cause I dont know what the max % is at full throttle because is saves the 96% at idle wich is actualy 4% .in reality. The 20% reading im getting at full throttle is REALY 80% duty cycle wich is accurate..... but it registers at 20% and does not save this important number cause it saves the HIGHEST % duty cycle.

few, i hope that im not cunfuzing u guys :)

could there be a setting on the acvr that could reverse the inj duty cycle % reading or something? If there is only one wire for this function i dont see how hooking it up to the wrong ecu wire would give me accurate but reversed inj dc %.....

3 points:

- Is there a setting on the AVC-R to reverse the duty cycle, uh, thingy? I doubt there is, because it doesn't make sense that it could be reversed to me. Maybe some cars use a common ground while others use a common + for the injector control (the RX-7 does this -- the ground side is what gets switched on/off by the ECU)? I guess it's possible.

- While it may appear that the numbers are inverse duty cycles, it could also just be a coincidence that the numbers go down as RPMs go up, and not really the inverse of the injector duty cycle.

- The peak injector duty cycle measurement may turn out to be faulty for the reason I mentioned above (false "high" values, which get saved as the peak). However, you can still put on the graph thingy or glance over at the display at ~7000 RPM under high boost and get a good idea of your max inj duty cycle values are.

-Max

With the AVC-R you can only read Inj duty OR RPM without rewiring it. You have yours hooked up to read RPM.

To get around that, I hooked up a SPDT switch. I can read either with the flip of a switch.

That's how I interpreted the manual, too -- RPM or inj duty, but not both. So I hooked it up to read RPM first, since I was interested in some of it's RPM-related boost control features. However, I later switched to the "inj duty" connection and the RPM readings still worked (and matched my tach & PowerFC readings). I haven't tested under deceleration fuel cut (I bet the RPM drops to 0), but the RPM reading seems to work otherwise and so does my inj duty cycle reading (with the exception of the false high values I mentioned earlier). This makes sense, since the injectors fire once per engine rotation -- it seems like the AVC-R could read both RPM and inj duty from the same signal as long as the injectors are firing.

I am not 100% certain of any of this since it has been a while since I installed the AVC-R and I just got my car back on the road after a long downtime. I haven't played with the AVC-R yet since I am still driving on low/no boost for break-in. It is quite possible that my memory is foggy. :D

Try putting your switch on "inj duty" and see if it still reads the RPMs correctly.

-Max

Okay, I just drove my car and checked the RPM and injector duty displays on the AVC-R. I have it hooked up for injector duty, and it works (reads correctly). RPM also works correctly, except when you let off the gas and the ECU stops firing the fuel injectors. RPMs drop to zero during this fuel cut period.

-Max

Ok it must be hooked up for rpm cause it does not drop to zero, so it is just guestimating the inj dc and i shouldnt trust it. its still weird that its doing it inversely tho. the rpm's on the avcr are about 200 lower than the gauge but from other posts ive read this seems normal. POSS, can u give me any details or a how to on the switch u hooked up? thnks for all the input

mine reads both accurately so it can be done...

howard coleman

Now that you mention it I have noticed that when I read rpm w/o flipping the switch, it read close. I thought is was a coincidence and didn't look at it long enough to figure out the correlation. Thanks guys! :)

lexidic, I would try to hook it up the other way (tap into the injector signal instead of rpm) and if that works, stick with that.

If you want to try it my way, just go to radioshack or somewhere to get a SPDT switch, run a lead from each signal wire(inj and rpm) to the outside contacts on the switch. Then hook up the center contact to the purple wire on the AVC-R. That's the abreviated version, if you have questions, let me know.